Polycultures are viewed as one of the ways in which sustainable food production could be promoted, as the interactions between the different species of plants, and with other above and belowground organisms help sustain ecosystem functions and preserve biodiversity, avoiding or minimizing the need for agrochemical inputs. The milpa is an agroecosystem of Mesoamerican origin typically conformed by maize intercropped with common beans and squash, among many other planned or unplanned plant species. It also serves as a habitat to a vast diversity of animals, fungi and other elements of associated biodiversity. The milpa has coevolved with originary peoples and local communities and is adapted to a variety of climatic, edaphic and cultural conditions, being the foundation of food security in many rural areas where it is reproduced by peasant families year after year. Yet, its value extends far-beyond the calories and nutrients it generates; it is central to rural livelihoods and culture in Mexico, and is a locus for in situ generation and conservation of biological and cultural diversity. Hundreds of native crop species and varieties, festivities, local practices and dishes, among others, are reproduced along with the milpa. As a diversified and locally adapted agroecosystem, it is key to mitigate and face current and future challenges, such as extreme droughts and climate change. The milpa involves and relies on diverse ecological processes, such as plant-plant and plant-animal interactions or biogeochemical cycling. It also involves complex ecological dynamics at different scales, ranging from soil microenvironments, to the plot, to the landscape-level. Being a dynamical agroecosystem, the milpa ecology, its contributions to people and its challenges change in time and space. In this symposium we aim at synthesizing and discussing the ecological knowledge currently available for this agroecosystem, including both general patterns and context-specific aspects. In a closing discussion forum, we also aim at identifying relevant avenues for further research and generating guidelines for inter and transdisciplinary work. We are convinced that a more nuanced understanding of these ecological processes, in dialogue with local and other types of knowledge, can contribute to the reproduction of milpa as part of working landscapes where people and biodiversity can thrive.